Transmission on wired, fiber optic, and wireless channels is limited by the signal power received via the direct channel and the noise present on the channel. A “channel” may be a pair of wires in a multi-pair cable, a radio frequency band, or signals transmitted to or from one of several radio antennas.
Crosstalk is a phenomenon by which a signal transmitted on one channel of a transmission system creates an effect in another channel. Crosstalk is usually caused by undesired capacitive, inductive, or conductive coupling from one channel to another. Vectoring is an active technology that cancels crosstalk between signals travelling down nearby copper pairs. The existing practice of vectoring can reduce the effects of far end crosstalk by adding a pre-coded component to the signal on other channels, but the pre-coded component does not increase the desired signal on the destination channel (the channel targeted for a performance boost).
Multiple-input and multiple-output, or MIMO is a method for multiplying the capacity of a radio link using multiple transmit and receive antennas to exploit multipath propagation. The existing practice of MIMO transmission can boost the signal received in a destination channel by sending coordinated signals on multiple channels, but it requires the added complexity of having multiple receivers.
Also, the reinforcing signals may also be transmitted on unused, coupled channels where the crosstalk into the destination channel would boost the desired signal, however exploiting only unused channels is limited by the number of available channels, the degree of coupling to the destination channel, and the added complexity of requiring additional transmitters to send the reinforcing signals on the spare line.
Channel bonding is a practice commonly used in IEEE 802.11 implementations in which two adjacent channels within a given frequency band are combined to increase throughput between two or more wireless devices. The existing practice of channel bonding achieves higher performance by sending a portion of the payload on each of several channels, however this comes at the cost of occupying multiple channels and requiring the complexity of additional transmitters and receivers.
There is a need to provide higher bit-rates while avoiding the complexity of needing additional transmitters or receivers when there are no unused (spare) channels.